The intent of this program-project grant is to investigate the epidemiology of breast cancer and benign breast disease. The work will include: the determination of epidemiologic characteristics of women diagnosed as having different histologically defined breast conditions; epidemiological and laboratory studies of the secretion of mutgenic substances into breast fluids, including their chemical characterization and potential DNA-damaging and repair activity on cells in human breast fluids and their metabolic activation by ray mammary tissue; epidemiologic investigations of estrogen-binding beta-globulin in blood and breast fluids; and research on the value and effects of breast cancer risk counseling.